It has well been known that a compound having a highly branched structure, for example, a dendrimer compound or a hyperbranched type polymer is markedly improved in functionality depending on its branched degree (Non-Patent Literature 1). As a preparation method of the compound having such a branched structure, there has been known mainly two methods, one of which is the convergent method, and the other is the divergent method. The convergent method is a method in which a branched state side chain is bonded to a core which locates at the center portion of a branched state compound at the final stage or near to the final stage, and has merits that purification of the side chain is relatively easy since it is a relatively low molecule, it is possible to introduce a high purity branched state side chain into the core and a branched state compound with high purity can be readily obtained. However, when a number of the branch at the side chain is large, there is a problem that apex of the side chain becomes bulky, so that reactivity to the core is lowered. In addition, the divergent method is a method in which a branch is successively extended to outward from the core, and when a branch in the side chain is omitted, compounds having different distributions are difficulty separated, so that a compound with good purity can be difficulty prepared. However, a branch is extended to the direction of the outside having a space so that there is a merit that lowering in reactivity due to steric hindrance is relatively a little whereby the reactivity is good.
Further, it has been disclosed that a dendrimer type siloxane having a branch has a low viscosity as compared to that of the conventional linear siloxane having the same number of the silicon atoms, and it becomes an excellent material as a mold releasing agent, a lubricant, a resin modifying agent, a crosslinking agent (Patent Literature 1). In addition, a siloxane dendrimer in which a dendrimer type siloxane is grafted to a polymerizable compound has been developed (Patent Literature 2). However, these siloxanes have narrow branched chain and are chemical structurally rigid so that they have poor flexibility, and as a grafted branched chain becomes larger (the generation is increased), there is a problem that an effect of steric hindrance appears, and reactivity of the polymerizable functional group becomes insufficient, whereby the third generation in which the branch becomes 3 units at one side chain has not yet been commercialized.
From the problems, it has been developed a method in which a siloxane chain had been tried to be introduced into an allyl ether compound (CH2═CHCH2OR) by hydrosilylation, but it has been known that in the olefins of the allyl ether compound, 10 to 20% thereof are internally rearranged to form a 1-propenyl ether product (CH3CH═CHOR) which becomes a main accessory component, and it has also been known that propionaldehyde is generated when the 1-propenyl ether is hydrolyzed by a moisture, etc., in the air, and it becomes a cause of generating bad odor from the final product, etc. To solve the problem of the odor, it has been disclosed a method in which a vinyl ether group at the inside of the 1-propenyl ether is reduced to a propyl ether (CH3CH2CH2OR) by a hydrogenation reaction using a hydrogen gas under pressure in an autoclave, whereby chemical decomposition is prevented and generation of bad odor is prohibited (Patent Literature 3), further, a method in which a solid acid is used at the time of a hydrogenation reaction whereby removal of generation of a bad odor substance can be realized, which solves the problem that an acetal is formed by reacting the decomposed aldehyde and an alcohol in some cases, and the acetal remains in the product without being reduced by the hydrogenation reaction, which gradually decomposes by a moisture or an acid, so that an odor from the product is continued to be released (Patent Literature 4), and a method in which propionaldehyde generated from a lower alcohol (R′OH) is subjected to an acetalizing treatment (CH3CH2CH(OR′)2) to make the bad odor component a low boiling point compound, which is removed by distillation (Patent Literature 5). However, these methods are coping methods for the purpose of suppressing generation of the bad odor component or removing the bad odor component, and are not the methods to basically suppress generation of an internal rearrangement product at the time of the reaction.
On the other hand, whereas it has been well known, it is possible to reduce an internal rearrangement product of the olefin at the time of a hydrosilylation reaction by using β-methallyl alcohol which is 2-methyl-2-propen-1-ol, but there are problems that a minutely produced isobutyraldehyde expels unpleasant odor, and further the cost of the β-methallyl alcohol used as a starting material is expensive as compared with that of the allyl alcohol.
Therefore, in a branched compound containing an ether bond having flexibility, it is difficult to synthesize a branched type siloxane with good purity due to the problem of the internal rearrangement, and when a silicone is tried to be introduced into the branched compound having an allyl group, if internal rearrangement of a byproduct of the hydrosilylation reaction is generated, the products one of which is a silicone chain symmetric cannot be obtained. When this is tried to be applied to pharmaceuticals, medical devices or foods, an asymmetric branched state compound is markedly affected to the effectiveness of the physiological activity due to the formation of the diastereomer in many cases. It has also been well known that it is a high degree of difficulty to introduce a positionally and sterically pure, and symmetric branched structure from the viewpoint of synthetic chemistry.